Genome-wide identification of lipases in the oriental armyworm, Mythimna separata Walker (Lepidoptera: Noctuidae)

Lipases are indispensable for animal digestion. Insects rely on lipases to catabolize lipids from food in immature stages, and to break down TAGs in adults that accumulated earlier in fat body to supply flight and reproduction. The oriental armyworm, Mythimna separata Walker (Lepidoptera: Noctuidae), is a migratory moth that damages crops and pastures in East Asia. We identified 85 lipases from the genome of M. separata, including 56 neutral lipases, 22 acid lipases, one lipase 3, one hormone-sensitive lipase (HSL), one lipase with Gly-Asp-Ser-Leu motif (GDSL), and four adipose-triglyceride lipases (ATGLs). The phylogeny, catalytic capacity, and expression of neutral and acid lipases were investigated. The majority of neutral and acid lipases contain the conserved GXLXG nucleophilic elbow, a Ser-Asp-His triad, and an active lid/flap, although the length of active site lids from neutral lipases was short (< 18 residues) compared to pancreatic lipases from mammals. The results of expression analyses indicated that about half of neutral lipases and 35% of acid lipases were highly expressed in 3rd instar larvae compared to egg, pre-pupal, pupal and adult stage. Our findings could contribute to a better understanding of the lipase family gene in moth species.